Moving-Coil Microphone
- Microphones convert sound waves into electrical current
- A moving coil microphone works using the principles of the generator effect
The moving coil microphone
- When sound waves reach the microphone, the pressure variations cause the diaphragm to vibrate
- This in turn causes the coil to move back and forth, through the magnetic field produced by the magnet
- As it does so, the coil cuts through the field lines
- This induces a potential difference in the coil
- The potential difference will be alternating because the coil is continually changing direction due to the vibrations of the diaphragm
Examiner Tip
Microphones and loudspeakers look very similar, but they do very different things. When tackling a question on either of them, make sure you are writing about the right one!
The explanation of the loudspeaker is very similar to the explanation of a motor, however direct current is used in a d.c motor and alternating current is used in a loudspeaker or headphone. You need to learn how both work.
When explaining how a loudspeaker works remember to refer to the alternating current and the changing magnetic field that it creates.
